Power steering too loose, no resistance or feel '72 sports roof 302 C-4

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Danno

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My steering has no feel, it's too "loose". I don't mean mechanically loose , I mean it has no feel, no feedback. It's like there's no weight on the front tires. I've "lived" with this since I rebuilt the front end. I think I remember hearing that there was a check valve or something that could be added to the steering system......any ideas? '
 
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My steering has no feel, it's too "loose". I don't mean mechanically loose , I mean it has no feel, no feedback. It's like there's no weight on the front tires. I've "lived" with this since I rebuilt the front end. I think I remember hearing that there was a check valve or something that could be added to the steering system......any ideas? '
First some questions;
1- do you know or can you give us the tag ID of the box. It ought to be SPA-S or U.
2- how many turns LTL.
3- if you measure at the top of the steering wheel, how far does it move left and right passed center without the motor running.
4- do you know if the box has been replaced or rebuilt.
So what you're saying is, when you drive the car, it feels like you can drive it with your little finger, correct?
More info would help here.
 

RIBS

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My 71 302 PS is the same, I would call it a 2 finger steer… I also am curious what’s normal for these cars, mine needs an alignment but otherwise is new components in suspension, old steering parts….
 
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Do the alignment first. Toe, caster and camber have a lot of effect on steering feel.
Very good point Mike.
However as WE all know, the numbers for radial tires are not the same listed in the manuals for bias ply tires.

"Open Tracker" shows for street specs;

Caster +2.5-4.5 degrees for PS.
Camber; 0 - -.5 degrees.
Toe; 1/8" in. I take it that means each side.
To achieve more than 3 degrees caster, it may require shims to be added
.
 
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Go with an alignment first to make sure you have plenty of caster. If the steering feel is not to your liking after the alignment (using the Open Tracker Racing specs that Geoff listed) then you have to choose your next move.

Option 1) Live with the steering feel.
Option 2) Pull the steering box out and send it out to a shop to have the control valve swapped. The feel (force before power assist takes over) is controlled by the diameter of a small torsion bar (Torsion spring) inside the control valve. The ones if the 71-73' are about .180" which is pretty anemic. I have a .210" one in mine, makes a huge difference. It is also possible to DIY swap the entire control valve with one that has a larger T-bar in it. If that interests you let me know.
 
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Go with an alignment first to make sure you have plenty of caster. If the steering feel is not to your liking after the alignment (using the Open Tracker Racing specs that Geoff listed) then you have to choose your next move.

Option 1) Live with the steering feel.
Option 2) Pull the steering box out and send it out to a shop to have the control valve swapped. The feel (force before power assist takes over) is controlled by the diameter of a small torsion bar (Torsion spring) inside the control valve. The ones if the 71-73' are about .180" which is pretty anemic. I have a .210" one in mine, makes a huge difference. It is also possible to DIY swap the entire control valve with one that has a larger T-bar in it. If that interests you let me know.
Bentworker, I know you've pulled many ps boxes apart along with torsion bars. Do you know off hand, what the T/bar diameter is for the SPA-T V/R box? If so, please let me know. I never went that far in a rebuild and still have a stock V/R control valve. Finding a .210" t/bar around here would be near impossible as no-one has any old "junk" laying around anymore. I know, I asked all the junk yards for miles around.
 

Hemikiller

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All of the components in the steering and suspension system have a certain amount of drag to them when they are rotated. Ball joints, tie rod ends, pitman and idler arm, even the steering box itself. This was all accounted for when the steering effort was set in product development. Fifty plus years later with worn in parts and loose seals and o-rings in the steering gear, with potentially mismatched PS parts and that effort will be much lower than designed. My 71 Squire wagon has "pinky" steering, it also has all it's original front end parts still in place.

In both Danno's and RIBS case, if all of the front end wasn't replaced/rebuilt, and I mean all, including the steering box, I'd start there first. Alignment or not, it makes a tremendous difference in feel.

Once that's done, then I'd use the alignment specs that Stanglover posted from Opentracker's site. 1/8" toe in is total toe - meaning the difference between the front and rear of the tires, measured at the same point on the tread.
 
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Bentworker, I know you've pulled many ps boxes apart along with torsion bars. Do you know off hand, what the T/bar diameter is for the SPA-T V/R box? If so, please let me know. I never went that far in a rebuild and still have a stock V/R control valve. Finding a .210" t/bar around here would be near impossible as no-one has any old "junk" laying around anymore. I know, I asked all the junk yards for miles around.
Looks like the variable ratio boxes have a t-rod that is about .190" compared to .185" in the fixed ratio boxes. I had to dig up the thread from when I built up my steering box back in 2016.
Intro...

So you want a quick ratio box in your Mustang? Better yet a quick ratio box with feedback that feels like a modern car instead of the "pinky finger" power steering it came with? It can be done, with wrecking yard parts and a moderate level of tools. Best yet it can be done with no change in the appearance of the steering box, and no modifications to your car. The GM A-body guys have it easy, since the Jeep Grand Cherokee box will bolt right up in their cars. However the Mustangs use a different casting, with different mounting points. There were no applications that used the 71-73 Ford mustang style Saginaw 800 casting with the 12.7:1 ball screw and piston. So if you want a quick ratio box you must swap in the 12.7:1 ball screw and piston out of a GM or Jeep vehicle that had one into your casting. The thread below is a general guide to what has to be done.


I started building up a steering box today. My 71' Grande had the super slow fixed ratio box. The variable ratio box came from another member on the forum. Add in a 91' Firebird 12.7:1 fixed ratio box and I have a mountain of mix and match parts. Goal is to use the Mustang casting, with the quick 12.7:1 firechicken ball screw and piston. Also going to use the firechicken input since it has a much larger T-bar (Torsion Bar). We'll see how it turns out, I was thinking of using the Mustang input shaft, but the T-bar (the thin little shaft I'm measuring with a caliper in a photo below) on both of the Mustang boxes was so tiny that I decided to go with the Firebird input. That means I will have to get an adapter rag joint since the splined input shaft is smaller. Hopefully it will be worth the trouble to get more feedback that the larger T-bar will offer.

These are all Saginaw 800 series boxes and the parts interchange minus the input shaft and the casting itself. This is a pretty neat DIY project and the 12.7:1 quick ratio gears are plentiful in many 1980's GM F Body (Camaro & Firebird) along with many of the Jeep Grand Cherokees. If you are go to a pick-n-pull yard you should be able to walk out including tax and core charge for less than $75.00 and have the parts you need minus a $30.00 rebuild kit from Rock Auto. The info on what exact models to harvest from is posted a few pages ahead.

Pictures...

You can see the differences in the internals.

Ball Screw. Quick ratio 12.7:1 ball screw in the bag on the far left, stock variable ratio in the center, slower fixed ratio on the right. Note the two lines between each "thread" on the 12.7:1 screw. This is unique to the 12.7:1 screw and can be used to identify it in a wrecking yard. Just remove the pitman arm, then unscrew the four bolts on the sector shaft cap. Make sure the steering is in the center of it's travel and pop the entire sector shaft and cap out (mallet from the bottom). With a flashlight you should be able to turn the junkyard box to full lock in one direction and see the ball screw. If it has the two lines like the one in the photo you are good to go!

View attachment 33437

Variable ratio sector shaft and piston. Note the deeper center tooth for the variable ratio.

View attachment 33438

Fixed ratio sector shaft and piston. Notice that all the teeth are the same depth. The fixed ratio teeth seemed to be identical to the GM F body ones.

View attachment 33439

.185" diameter torsion bar out of the SPA S fixed ratio box. This is pretty small and is why the stock steering boxes take so little effort to turn with next to zero feedback. Larger torsion bars = more feedback. You should never take apart an input assembly this far if you intend to reuse it. I took it apart for learning.

View attachment 33440

Slightly larger .190" torsion bar out of the variable ratio SPA AF box. Still small but better.

View attachment 33441
 
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